This invention relates to a leveling system for use with a vehicle, such as a recreational vehicle.
Various systems are known for leveling a vehicle such as a recreational vehicle. Some such systems are shown in U.S. Pat. Nos. 4,061,309; 4,165,861; 4,597,584; 4,743,037; and 4,746,133. These patents all show a leveling system having four jacks located one adjacent each corner of the vehicle. Schneider et al U.S. Pat. No. 5,176,391, owned by the same assignee as the present application, discloses a vehicle leveling system having three jacks, two of which are located at the rearward end of the vehicle and one of which is located at the forward end of the vehicle.
Generally, all of the above-noted patents disclose vehicle leveling systems which are relatively complex in construction and operation, to provide automatic leveling of the vehicle in response to certain operator commands.
It is an object of the present invention to provide a manually operated semi-automatic vehicle leveling system which is relatively simple in its components, installation and operation. A further object of the invention is to provide several features for use with a manually operated vehicle leveling system which enhance operation of the system and simplify the leveling process for the operator.
In accordance with one aspect of the invention, a vehicle leveling system includes a series of extendible and retractable jacks mounted to the frame of the vehicle, a manually operated actuator mechanism located within the vehicle interior, and a power system interposed between the jacks and the manually operated actuator mechanism for selectively extending and retracting the jacks. In the above-noted patent applications, the series of jacks includes first and second jacks located toward one end of the vehicle and a third jack located toward the opposite end of the vehicle. The form of the invention in the present application includes a fourth jack also located towards the opposite end of the vehicle which is operated in parallel with the third jack. This form of the invention is referred to as a pseudo four-leg form of the invention. The pseudo four-leg form of the invention minimizes frame twist.
The manually operated actuator mechanism includes a series of switches disposed in a diamond pattern relative to the longitudinal axis of the vehicle. The switches may be in the form of four manually actuated switches mounted to a panel located in the interior of the vehicle. In one form of the invention, a level sensing device is located in the vehicle interior to provide a visual indication to the operator of the attitude of the vehicle relative to level. In a semi-automatic form of the invention, a level sensing device is mounted to the frame of the vehicle and is interconnected between the switches and jacks to provide visual indications to the operator of which switches should be actuated to level the vehicle, and to output a signal when the vehicle has attained a level condition. Circuitry is interconnected between the level sensing device and the switches for controlling operation of the jacks and to cut-off movement of each jack when the vehicle has attained a level condition in the vicinity of the vehicle which is being raised or lowered by movement of the jack.
Each jack is preferably in the form of a hydraulic cylinder assembly including a cylinder and an extendible and retractable piston mounted to the cylinder. A spring is interposed between the cylinder and the piston. Introduction of pressurized fluid into the cylinder causes extension of the piston against the force of the spring, and the spring causes retraction of the piston when fluid pressure within the cylinder is relieved. A shoe is connected to the extendible and retractable piston, and the spring is preferably interconnected between the cylinder and the shoe. The power system is preferably a fluid power system consisting of a hydraulic fluid reservoir, a pump for selectively supplying fluid under pressure to the jacks from the reservoir, and a control valve interposed between the hydraulic fluid reservoir and each jack. Each control valve controls the supply of pressurized fluid to one or more of the jacks during operation of the pump, and also provides flow of fluid to the reservoir when the pump is not operating. In the pseudo four-leg form of the invention, the third and fourth legs are in fluid communication with each other, and share a common control valve. The control valves are responsive to operation of the manually actuated switches for selectively adjusting the attitude of the vehicle relative to level in response to manual actuation by the operator. Each control valve is interconnected with a single return line interconnected with the reservoir, and a return control valve is disposed in the return line for controlling flow of fluid from the jacks to the reservoir. The return control valve is responsive to a manually operated retract switch actuable by the operator and located within the interior of the vehicle.
The invention further contemplates a unique jack construction for use in the vehicle leveling system of the invention. A plate is interconnected with the hydraulic cylinder of each jack toward the upper end of the cylinder. The spring is interconnected between the plate and the piston, preferably having its lower end mounted to the shoe to which the piston is connected. A connector arrangement is interposed between the spring and the plate for securing the spring to the plate. The connector arrangement is preferably in the form of a tapered passage provided in the upper end of the spring, which decreases in transverse dimension in a bottom-to-top direction, a plug having a tapered wall disposed within the tapered passage and engaging the spring, and a connector extending between the plate and the plug. The plate is mounted to the upper end of the cylinder so as to be selectively pivotable relative thereto. In this manner, the spring can be placed in any desired position relative to the vehicle frame once the cylinder is mounted to the frame in order to avoid any obstructions which may be present in the vicinity of the frame.
The invention further contemplates several features providing semi-automatic operation of the vehicle leveling system, to provide ease in operation of the system. A level sensor is mounted to the vehicle and is interconnected with the jacks and with the switches. An operating system is interposed between the jacks and the switches for moving the jacks in response to operation of the switches, and for cutting off movement of each jack in response to detection of a level condition of the vehicle, by the level sensor, in the vicinity of the vehicle in which each jack is operable to adjust the elevation of the vehicle. This assists the operator in operating the jacks to achieve a level condition for the vehicle. In addition, a signal arrangement is provided for alerting the operator as to which of the plurality of switches should be actuated to operate the jacks to adjust the elevation of the vehicle in order to level the vehicle. The signal arrangement is preferably in the form of a selectively illuminable visual indicator, such as an LED, located adjacent each of the switches. The visual indicator is illuminated to alert the operator that the adjacent switch should be actuated in order to level the vehicle. As can be appreciated, the combination of the automatic cut-off feature and the visual indicator feature greatly assists the operator in manipulating the switches to level the vehicle. As a further added feature, the level sensor is capable of providing an output signal when the vehicle frame is at an angle relative to level which exceeds the adjustment capability of one or more of the jacks. A signal, such as a visual indication, is provided to the operator responsive to the signal to alert the operator of an excess slope condition. This saves the operator time by allowing the operator to move the vehicle on the terrain to a location which obviates the excess slope signal. In the past, an excess slope signal was only output when one or more of the jacks had been fully extended and the vehicle could not at that time be leveled. As an additional feature, the invention contemplates a latching retract or extend arrangement interconnected between the switches and the jacks. In either form the latching feature allows the operator to press a single switch to begin extension or retraction of the jacks, and to then release engagement of the switch. The jacks continue to extend or retract to a desired position without engagement of the switch by the operator. In a latch retract mode, all jacks are fully retracted after initial engagement of the switch. In a latch extend mode, all jacks are extended until each jack engages the ground, after which extension is stopped in response to a predetermined threshold of hydraulic pressure in the hydraulic circuit, and the jacks are then operated individually to level the vehicle.
The above-noted semi-automatic and pseudo four-leg features can be employed alone or in any combination, as desired, to enhance operation of the vehicle leveling system.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.